<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>知乎案例</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .box{
            width: 500px;
            height: 1000px;
            background: yellow;
            margin: 0 auto;
        }
        body{
            background-image: url(知乎img/zhihu.png);
            background-size: cover;
            background-attachment: fixed;
        }
    </style>
</head>
<body>
    <div class="box">
        
    </div>
</body>
</html>